Good morning! so ive had this problem for a little while now and i have been trying to solve it but with no luck... when the car is revved up high but not always to the limiter just revved up high it will sometimes just randomly start missfiring, this will last for just 10-20seconds aslong as i keep driving very steadily. But once it clears up it works perfectly fine again! However it happened again yesterday morning but the worst it has done it. I had to pull over because it was popping and banging and had zero power. As soon as i pulled over it died and took atleast 2 minutes to restart, while cranking though it sounded awful, almost as if the timing was out, it sounded like there was no compression and it was popping etc. anyway it eventualy started up again on what sounded like 1 cylinder and then it gradualy came back a cylinder at a time and then was perfectly fine again! as you can imagine its really fucking me off now, mid drift it will start missfiring which is far from ideal! Anyway i am running around about 16psi with all correct supporting mods except bigger injectors. I have run the car at standard boost and it makes no difference. I have replaced the coilpacks with a known good working set, it has the correct heat range plugs in. I dont want to just throw money at parts until its solved, i would rather have input from other people and buy parts with a reason! please please please can someone help!
I no it sounds stupid but boost leak i checked mine before and missed the smallest hole mine done the same have u made sure ther are no cracks etc on coilpacks another mistake i made before is putting the rubber of a coilpack on my s13 upside down lol have u tried a second hand maf ? Take one plug out at a time and crank the engine to check for spark maybe possible injectors ? Coukd be allsorts good luck
Should have mentioned i have already done a boostlesk test and all is good, also the coil packs are definetly good as they arr a good known working set i bought, havent actualy tried the maf yet but it was next on my list, i just wanted to see if anyone on here could shed some light in the meantime... Also while i am here how could i check for problems with the injectors?
its a long shot, but... if its only happening near the limiter it COULD be... weak valvesprings causing valve float and hydraulic lifter pump up. It is a long shot, however its reasonably common in SRs getting limiter bashed cos the stock springs are soft as shite. I've had it myself. It doesnt do it regularly, just once in a while (seems to happen more easily if being stupid and doing a gay doughnut in 1st bashing off the limiter for ages). Your symptoms seem to match lifter pump up. Higher boost will exacerbate the problem with valve float so I would try running stock boost for a while and see if it stops it or at least helps it.
Thanks for your input! I had kind of thought that myself but dissmissed it, although i have found that the level of boost doesnt actualy make a difference. Could a bee r with a lower limit be an answer if this is whats happening?
Actualy the more i think about it the more i think you could be right... When it died the other day and wouldnt start it sounded like it had no compression which i suppose would fit with the lifters being pumped up. And then the way the missfire gradualy goes away as if the lifters are slowly releasing the pressure?
i once had a z32 afm that when code read it gave me 55 even though it was fecked. have you cleaned your afm element recently? have you tried driving with the lambda disconnected? ever changed the fuel filter could be blocked? if u have check the fuel hose isnt kinked.
Didnt know i could run with the lambda disconnected? I may try that in the morning. I have replaced all the hoses when i first got the car as they were all perished, and i am also already using the bigger z32? Fuel filter.
Well i have got to work with the lambda disconnected and noticed no weird running problems, i havent had the chance to put my foot down and check for the missfre yet though so will see what its on my way home tonight
what plugs are you using and how old are they? What size gap are you running? Do you have a wideband?
i think they may be 8's and ime not sure on the gap as i fitted them atleast a year ago... Yes i have an aem wideband but i seem to have killed 2 sensors and i havent got around to buying a 3rd yet but i always found it hard to read as the values would flick around so quickly
